Simultaneous production of alcoholates and trivalent titanium complexes of beta-diketones

ABSTRACT

Tetravalent titanium alcoholate-beta diketone complexes, e.g. titanium isopropylate-triacetylacetonate, are reacted with an alkali metal amalgam in a non-polar solvent to reduce the titanium to trivalent state, forming, for example, titanium triacetylacetonate and sodium isopropylate. The sodium isopropylate is a crystalline precipitate which can be removed by filtration; the amalgam can be decanted off and reused, as in alkali metal chloride electrolysis, to restore its alkali metal content so as to be ready for re-cycling.

United States Patent [1 1 Termin et a1.

[ 51 Feb. 13,1973

1541 SIMULTANEOUS PRODUCTION OF ALCOHOLATES AND TRIVALENT TITANIUMCOMPLEXES OF BETA- DIKETONES [75] Inventors; Erich Termin, Laufenburg;Gerhard llauck, Troisdorf-Sieglar, both of Germany [30] ForeignApplication Priority Data Sept. 6, 1969 Germany ..P 19 45 303.3

[52] U.S. Cl. ..260/429.5, 260/429 .1, 260/632 A [51 1 Int. Cl. ..C07f7/28 [58] Field of Search ..260/429.5, 632 A, 429 J [56] ReferencesCited UNITED STATES PATENTS 2,000,329 5/1935 Heisel et a1. ..260/632 A3,002,854 10/1961 Brill ..260/429.5 X 3,004,863 10/1961 Gray et al...260/429.5 X 3,061,623 10/1962 Mador et al ..260/429.5

FOREIGN PATENTS OR APPLICATIONS 1,081,880 5/1960 Germany ..260/429.51,091,105 10/1960 Germany ..26()/429.5

OTHER PUBLICATIONS Chem. Abstracts, Vol.50, 15413d (1956) Chem.Abstracts, Vol. 48, 9254a (1954) Chem. Abstracts, Vol. 52, 2719g (1968)MacCorquodale et al., J. Amer. Chem. Soc. Vol. 50, pp. mas-1,939 1928Primary Examiner-H. Sneed Attorney-Burgess, Dinklage & Sprung [57]ABSTRACT Tetravalent titanium alcoholate-beta diketone complexes, e.g.titanium isopropylate-triacetylacetonate, are reacted with an alkalimetal amalgam in a non polar solvent to reduce the titanium to trivalentstate, forming, for example, titanium triacetylacetonate and sodiumisopropylatc. The sodium isopropylate is a crystalline precipitate whichcan be removed by filtration; the amalgam can be decanted off andreused, as in alkali metal chloride electrolysis, to restore its alkalimetal content so as to be ready for re-cycling.

9 Claims, No Drawings SIM ULTANEOUS PRODUCTION OF ALCOHOLATES ANDTRIVALENT TITANIUM COMPLEXES OF BETA-DIKETONES The present inventionrelates to the reduction of the titanium in tetravalent titaniumalcoholate betadiketone complexes by means of alkali metal, present asan amalgam, to yield trivalent titanium Betadiketone complexes andalkali metal alcoholates.

It is known that beta-diketone complexes of trivalent titanium can beprepared by reduction of beta-diketone complexes of tetravalent titaniumdissolved in organic solvents. As reducing agents, there have been usedorganometal compounds, viz. alkyl and aryl compounds of the metals ofmain Groups 1, II and ll] of the periodic system such as p-tolyllithium,phenylmagnesium bromide and diethylaluminum monochloride, and metals andmetal compounds, such as magnesium, zinc, sodium and chromium-(ll)chloride. As tetravalent titanium-containing complexes to be reduced bythis method, either pure beta-diketone complexes or complexbeta-diketone-titanium-IV halides may be used. This known method,however, has several drawbacks including the fact that the solutionswhich result have dissolved therein both the desired end product andundersired byproduct. A separation of these dissolved substances byevaporation of the solvent and subsequent sublimation is verycomplicated. Furthermore, the separation of the solutions, e.g. fromexcess zinc dust, is difficult because of a tendency of the solids toremain suspended.

In another vein, it is known to make alkali alcoholates by decompositionof alkali metal amalgams with alcohols. Industrially, this method isused, however, only with methyl and ethyl alcohols, as can be inferred,for example, form the treatise in Russian Chemical Review, Vol. 34, No.3, P. 161 185 (1965). With higher alcohols, the reaction proceeds onlyvery slowly and with poor yields based on amalgam. Therefore, a directconversion of the alcohols with the expensive, pure alkali metals athigher temperatures is generally avoided in these cases. One could,however, also use other expensive methods, such as for example thedecomposition of alkali metal hydrides with alcohols and the reaction ofalkali metal amines with alcohols in liquid ammonia etc., as likewisedescribed in the above literature.

In the normal amalgam decomposition with alcohols considerable effortmust be expended in the processing and concentration of the reactionproducts. With the higher alcoholates, in consequence of the hightemperatures required to concentrate the raw product, a yellowing of theproduct often takes place.

It is accordingly an object of the invention to provide simpletechniques to effect the reduction of tetravalent titanium complexes andsimultaneously to effect the production of alkali metal alcoholates, thedesired products being obtained in high yield and being readilyrecoverable.

In accordance with the present invention there is I provided a processwherein a tetravalent titanium alcoholate-complex of a beta-diketone isreacted with an alkali metal amalgam in a non-polar organic solvent. Thereaction proceeds at ambient temperatures although temperatures as lowas C. and as high as 120 C. may be employed. Alkali metal alcoholateprecipitates from the solution and may be separated by filtration fromthe dissolved trivalent titanium complex which contains one lessalcoholate group than initially.

Titanium-IV-alcohol beta-diketone complexes suited as starting materialsare monoalcoholate-tri-betadiketones, dialcoholate-di-beta-diketones andtrialcoholate-mono-beta-diketones. According to the invention, thepreferred procedure is to form the betadiketone complex in situ bymixing in an enameled vessel the respective titanium tetraalcoholate andthe respective diketone in the molar ratio 1:3, 1:2 or 1:1. Possiblycooling may be necessary since the reaction is exothermic. Thetetravalent titanium-alcoholatebetadiketone complex then formsinstantaneously. As starting substance, themono-alcoholate-tri-beta-diketone is preferred, i.e. the reactionproduct of the tetraalcoholate and three moles of beta-diketone.Preferred betadiketones include acetylacetone (pentanedione-2,4), estersof acetoacetic acid such as ethyl acetoacetate, and the like.

As alkali metal amalgams, sodium and potassium amalgams obtained inelectrolysis of their halides are preferred. The amalgams usuallycontain about 0.2 to 0.4 percent by weight of the alkali metal.Preferred are amalgams containing about 0.4 percent by weight of alkalimetal. Preferably the alkali metal is used in excess related to thetitanium, desirably from about 1.2 to 1.8 times the stoichiometric molaramount, i.e. in about 20 to percent excess.

As solvents for the process according to the invention those organicsolvents are used in which the resulting trivalent titanium-betadiketone complexes are soluble, and in which the simultaneously producedalkali metal alcoholates, on the other hand, are insoluble. Suitedtherefore are aromatic, e.g. monocyclic, hydrocarbons such as benzene,toluene, xylene and mixtures thereof, and also mixtures of aromaticswith aliphatics and/or cycloaliphatics, such as the hydrocarbons hexane,heptane and cyclohexane. According to the invention, the solvent ispreferably used in about 1 to 9, and preferably about 3 to 9 times theweight of the tetravalent titanium-alcoholate-beta-diketone complex,i.e. the concentration of complex in solvent, excluding othersubstances, is about 10 to 50 percent by weight, preferably 10 to 25percent by weight.

In the method according to the invention the preferred procedure is tofirst place the alkali metal amalgam and the solvent in an enameled orglass vessel, and then slowly add, under agitation and cover of aprotective gas (preferably nitrogen), the previously preparedtetravalent titanium-a1coholate-betadiketone complex.

Surprisingly, the conversion according to the invention, despite therelatively low concentration of the reaction partners, proceeds smoothlyand with quantitative yields based on the alkali metal content of theamalgam. Preferably, room temperature is used although lower and highertemperatures, e.g. between 0 and C, can also be used insofar asoperation at higher temperatures is permitted by the boiling points ofthe solvents.

The alkali metal alcoholate is obtained in crystalline form, while thecomplex solution turns deep blue to violet. The entire resultantsuspension can in simple manner be separated from the amalgam or mercuryby drawing off the latter or by decantation.

The thus present end products, viz. the alkali metal alcoholate and thesolution of the beta-diketone complex of the trivalent titanium, may beseparated from each other by filtration under a protective gas cover.The alkali metal alcoholate is washed with the respective solvent andthen, preferably in vacuum and a temperatures of about 50 C., dried toyield pure, white crystals. I

In many cases, the filtrate, i.e. the solution of the beta-diketonecomplex of trivalent titanium can be used directly or it can beconcentrated partially or completely by distilling off the solvent.

The amalgam or mercury separated from the products obtained according tothe invention and impoverished in alkali metals may, if desired, bewashed with the respective organic solvent and recycled to the alkalielectrolysis in which it will become enriched with alkali metal so as tobe capable of re-use in the process.

As advantages of the method according to the invention, two desirableproducts are obtained by a simple procedure at the same time. A verycomplicated separation of solutions of the end products and of solutionsof try-products is unnecessary, a simple filtration sufficing instead.Likewise the expensive sublimation and separation of suspension-pronesolid reducing agents, previously required, are no longer necessary.

By this process it is possible to obtain especially effectively andeasily the alkali metal alcoholates of the higher alcohols, e.g.branched alkanols of three to 18 carbon atoms, whose production by priorart methods is difficult and highly expensive.

Both alkali metal alcoholates and beta-diketone complexes of trivalenttitanium are of considerable importance for industry. Alkali metalalcoholates are used, as is known for example, as condensation catalystsin the organic synthesis of pharmaceuticals and the like. The trivalenttitanium complexes find application, for example, as polymerizationcatalysts and are also suited as anti-knock compounds.

The invention thus constitutes an important enrichment of technology.

The invention will be further described with reference to the followingexamples wherein all parts are by weight unless otherwise expressed.

EXAMPLE 1 In an enameled vessel with cooling device and stirrer, therewere added to l98.0 kg of titanium tetraisopropylate 209.0 kg ofacetylacetone over a period of 60 minutes. There then formed titaniumisopropylatetriacetylacetonate.

Into a second enameled vessel with a slowly running agitator there wereintroduced 960.0 kg of benzene and 5,600 kg of sodium amalgam, from asodium chloride electrolysis, containing 0.4 percent by weight ofsodium. To this mixture, over 200 minutes there was slowly added thepreviously prepared, dissolved titanium complex. A deep blue suspensionresulted. After comple' tion of the reaction, the amalgam layer wasdrawn off and recycled to the sodium chloride electrolysis, thesuspension then being filtered under exclusion of air. The filtrateconstituted an approximately 20 percent by weight solution of titaniumtriacetylacetonate. The residue from the filtration was washed withbenzene and dried under vacuum at 50 C.

The yield of sodium isopropylate amounted to kg (i.e. 87 percent of thetheory based on sodium in the amalgam). The yield oftitanium-triacetyl-acetonate was maximal, i.e. approximately 100 percentof theory based on starting titanium.

EXAMPLES 2, 3 and 4 The same procedure was followed as in Example 1,except that instead of sodium amalgam and titanium tetraisopropylate,potassium amalgam and titanium tetrabutylate were used, the solvent wastoluene and different titanium complex concentrations were employed. Thepotassium content in the amalgam was 0.3 percent by weight. In all threeexamples, potassium-nbutylate and a solution oftitanium-triacetylacetonate were obtained.

The test conditions and results are given in the table that follows.

The same procedure as in Example 1 was followed. The amounts of thestarting substances used were as follows:

426.0 g titanium tetraisopropylate 450.0 g. acetylacetone l ,200 mlbenzene 19.0 kg sodium amalgam (0.3 percent sodium) An approximately 28percent by weight solution of titanium-triacetylacetonate was obtainedalong with 168 g of sodium isopropylate.

EXAMPLE 6 The same procedure as in Example 5 was followed, except thatinstead of 450 g of acetylacetone, 585 g of ethyl acetoacetate wasemployed and, instead of sodium amalgam, 20.0 kg of potassium amalgam(0.22 percent by weight) were used.

The run gave g of potassium isopropylate and a blue-violet coloredsolution containing titanium tris- (ethyl acetoacetate) to the extent ofabout 32 percent by weight.

it will be appreciated that the instant specification and examples areset forth by way of illustration and not limitation, and that variousmodifications and changes may be made without departing from the spiritand scope of the present invention.

What is claimed is:

l. The process which comprises reacting a complex of tetravalenttitanium and from 1 to 3 times the molar amount of a beta-diketoneselected from the group consisting of pentanedione and esters ofacetoacetic acid, the balance of the titanium valences being complexedwith an aliphatic alcohol containing from three to 18 carbon atoms, withan alkali metal amalgam in a non-polar organic solvent, to produce atrivalent titanium-betaldiketone complex and alkali metal alcoholate.

2. The process according to claim 1, wherein the amalgam is used inexcess up to 1.8 times the stoichiometric amount of the tetravalenttitanium complex.

3. The process according to claim 1, wherein the reaction product isdecanted to separate it from the amalgam and is filtered to remove solidalcoholate, there remaining a solution of the titanium complex in thesolvent.

4. The process according to claim 3, wherein the amalgam is passed to analkali metal chloride electrolysis for replenishment of its alkali metalcontent to a concentration of about 0.2 to 0.4 percent by weight, therestored amalgam then being recycled for further reaction.

5. The process according to claim 2, wherein the alkali metal is presentin at least about 20 percent excess relative to the tetravalent titaniumcomplex.

6. The process according to claim 1, wherein the tetravalent titaniumcomplex comprises three molecules of beta-diketone and one of saidalcohol.

7. The process according to claim 1, wherein said non-polar solventcomprises a major amount by volume of an aromatic hydrocarbon.

8. The process according to claim 7, wherein the balance of said solventcomprises an aliphatic or cycloaliphatic hydrocarbon.

9. The process according to claim 8, wherein the tetra-valent titaniumcomplex comprises three molecules of beta-diketone and one of saidalcohol and is formed in situ from titanium tetraalcoholate andbeta-diketone, the amalgam being used in about 20 to percent excessbased on the titanium, the reaction product being decanted from theamalgam and being filtered to remove solid alkali metal alcoholate fromthe solution of titanium tri-beta-diketone complex, the amalgam beingpassed to an alkali metal chloride electrolysis for replenishment of itsalkali metal content to a concentration of about 0.2 to 0.4 percent byweight, the restored amalgam then being recycled for further reaction.

1. The process which comprises reacting a complex of tetravalenttitanium and from 1 to 3 times the molar amount of a beta-diketoneselected from the group consisting of pentanedione and esters ofacetoacetic acid, the balance of the titanium valences being complexedwith an aliphatic alcohol containing from three to 18 carbon atoms, withan alkali metal amalgam in a non-polar organic solvent, to produce atrivalent titanium-beta-diketone complex and alkali metal alcoholate. 2.The process according to claim 1, wherein the amalgam is used in excessup to 1.8 times the stoichiometric amount of the tetravalent titaniumcomplex.
 3. The process according to claim 1, wherein the reactionproduct is decanted to separate it from the amalgam and is filtered toremove solid alcoholate, there remaining a solution of the titaniumcomplex in the solvent.
 4. The process according to claim 3, wherein theamalgam is passed to an alkali metal chloride electrolysis forreplenishment of its alkali metal content to a concentration of about0.2 to 0.4 percent by weight, the restored amalgam then being recycledfor further reaction.
 5. The process according to claim 2, wherein thealkali metal is present in at least about 20 percent excess relative tothe tetravalent titanium complex.
 6. The process according to claim 1,wherein the tetravalent titanium complex comprises three molecules ofbeta-diketone and one of said alcohol.
 7. The process according to claim1, wherein said non-polar solvent comprises a major amount by volume ofan aromatic hydrocarbon.
 8. The process according to claim 7, whereinthe balance of said solvent comprises an aliphatic Or cycloaliphatichydrocarbon.